Grammatical methods for situation and threat analysis

Force deployment analysis with generalized grammar

“…Each overall force deployment hypothesis is a set of facts within a knowledge base and can be regarded as a possible world [54] constructed so as to make it easy to extract responses to the most important queries. Following the earlier work of McMichael et al [1,55], we show that an approach based on a context-free grammar (CFG) is capable of satisfying this requirement. We give an algorithm that scalably finds the maximum a posteriori probability (MAP) force deployment assessment both in batch and incrementally.…”

“…These requirements motivated McMichael et al [1] to suggest composable tree structures in which the nodes represent a given component of a force structure for an interval of time. Such situation components are said to cover a set of force objects.…”

“…In our analysis of the requirements of situation analysis, we suggested that a force deployment assessment is a spatio-temporal model that specifies the evolution of force structure and the activ- 1 If the language has at least one predicate of valence at least 2 that is not equality it is undecidable. However, if a well-formed formula is true it is possible to construct an algorithm that will halt to verify its truth.…”

“…Its children are listed as slots, and its begin and end times are given. While situation trees can be extracted using semantics alone under the ontology detailed in [1], they can be estimated probabilistically and more efficiently using a sequence-set grammar. The grammar implicitly imposes constraints that in a purely semantic solution would have to be enforced by explicit axioms (Section 5 et seq.…”

“…We applied an A* agenda-based parsing algorithm [82] which uses leaf-node normalisation to estimate the path completion cost [1] and satisfies the admissibility conditions [83]. A virtue of this algorithm is that while it is normally terminated at the optimum solution, it can be run on to provide a sequence of alternative hypotheses in order of decreasing probability.…”